The invention relates to processes for cleaning a container testing apparatus having gas sampling elements which can be lowered into the containers and a distributor device for successively dispensing the gas samples withdrawn from the containers to an analyzing instrument. The invention also relates to a container testing apparatus with a plurality of sampling elements which can be lowered into the container and an arrangement for cleaning a container testing apparatus having a stationary distributor head part and a moving distributor head part and pipes leading from said moving part to sampling elements which can be lowered into containers for testing.
With returnable bottles, in particular with plastic bottles, such as PET bottles, which cannot be washed at high temperatures, the problem arises that contamination must be reliably detected in order that contaminated bottles can be removed and/or diverted from refilling. In particular, it is necessary to be able to detect returned bottles which have been used by individual users for potentially dangerous substances (poisons, solvents). It is an already known procedure to take a gas sample from each bottle for this purpose and to analyse the sample by a suitable method, e.g. by photoionization detection (PID) or mass spectroscopy. The presence of even small traces of undesired substances in the bottle and/or in the plastic material can be detected in this way. Industrial testing apparatus with a high bottle throughput (of e.g. 250 to 700 bottles per minute) which test the bottles in this manner are available on the market.
It has been found that the cleaning of a testing apparatus of this kind, possessing a large number of sampling tubes for withdrawing the gas samples, is a laborious process involving relatively extended stoppage times. Nevertheless frequent cleaning is necessary in order that sensitive detection of foreign substances can actually be achieved.